The present invention relates to a refrigerator oil composition and more particularly to a refrigerator oil which is excellent in extreme pressure properties and anti-wear properties and further is excellent in stability in the presence of refrigerants.
A refrigerator oil which is used in lubrication of sliding parts of a refrigerator is required to have good extreme pressure properties and anti-wear properties. In recent years, with employment of the inverter system in refrigerators, a refrigerator oil having excellent exteme pressure properties and anti-wear properties has been increasingly needed.
In order to impart extreme pressure properties and anti-wear properties to a refrigerator oil, it has been proposed to add phosphorus compounds to the refrigerator oil (see Japanese Patent Application Laid-Open No. 88007/1978, for example). Of these phosphorus compounds, tricresyl phosphate (TCP) is most widely used.
Refrigerator oils with the known phosphorus compounds added, however, are unsatisfactory in extreme pressure properties and anti-wear properties. In particular, a TCP added refrigerator oil has disadvantages in that (1) extreme pressure properties and anti-wear properties are poor, and (2) the stability in an atmosphere of a refrigerant is poor.